Since the early 1980s, adjustable gastric bands have provided an effective alternative to gastric bypass and other irreversible surgical weight loss treatments for the morbidly obese. The gastric band is typically wrapped around an upper portion of the patient's stomach, forming a stoma that restricts food passing from an upper portion to a lower portion of the stomach. When the stoma is of the appropriate size, food held in the upper portion of the stomach provides a feeling of fullness that discourages overeating. However, initial maladjustment or a change in the stomach over time may lead to a stoma of an inappropriate size, warranting an adjustment of the gastric band. Otherwise, the patient may suffer vomiting attacks and discomfort when the stoma is too small to reasonably pass food. At the other extreme, the stoma may be too large and thus fail to slow food moving from the upper portion of the stomach, defeating the purpose altogether for the gastric band.
In addition to a latched position to set the outer diameter of the gastric band, adjustability of gastric bands is generally achieved with an inwardly directed inflatable balloon, similar to a blood pressure cuff. The inner diameter of the gastric band may thereby be adjusted by adjusting the pressure in the balloon. Typically, a fluid such as saline is injected into the balloon through a fluid injection port to achieve a desired diameter. Since adjustable gastric bands may remain in the patient for long periods of time, the fluid injection port is typically installed subcutaneously to avoid infection, for instance in front of the sternum. Adjusting the amount of fluid in the adjustable gastric band is typically achieved by inserting a Huber tip needle through the skin into a silicon septum of the injection port. Once the needle is removed, the septum seals against the hole by virtue of compressive load generated by the septum. A flexible conduit communicates between the injection port and the adjustable gastric band.
The traditional surgical technique for securing a fluid injection port developed for vascular uses has been applying sutures through a series of holes spaced about a peripheral base flange. While generally effective, suturing often proves to be difficult since adjustable gastric bands are intended for the morbidly obese. A significant thickness of fat tissue may underlie the skin, causing difficulties as the surgeon attempts to apply sutures to deeply recessed tissues (e.g., 10-12 cm) to secure the port, often requiring 10-15 minutes to complete.
In addition to the difficulty of installing an injection port, the use of injections and injection ports for adjusting gastric bands has other disadvantages apparent to those of ordinary skill in the art. For example, port-site infections are a common complication arising from the use of injection ports. In addition, the use of needles or other invasive techniques to adjust a gastric band may subject a patient to unnecessary discomfort.
The art includes some gastric band adjustment systems that do not require the use of injections or injection ports, such as employing an electrical motor that adjusts the volume of a bellows accumulator. Power to such an implant is generally provided by transcutaneous energy transfer (TET), with control and/or feedback provided by telemetry. Such TET systems have to overcome design challenges associated with electromagnetic interference and compatibility (EMIC). In addition, a clinician who adjusts the adjustable gastric band has to invest in the external equipment necessary for TET.
Implant systems exist that employ the use of manually palpable pumps and valve assemblies in the context of penile implant systems. An example of such a system is disclosed in U.S. Pat. No. 4,404,968, issued to Evans. However, in contrast to the present invention, such penile implant systems employ the use of generally linear bladders as opposed to adjustable sphincters. In addition, such penile implants provide obvious visual feedback as to which direction the fluid in the implant system is flowing. The pumps in many conventional penile implant systems are bulbs located in the scrotum, such that the pump may be easily palpated by hand through relatively thin skin by squeezing both sides of the bulb.
Accordingly, it would be advantageous to have an implantable system whereby an adjustable sphincter, such as a gastric band, may be adjusted without the use of an injection or injection port. It would be further advantageous to have such a system that avoids the inconveniences of conventional TET implant systems. Consequently, a significant need exists for an implantable adjustable sphincter system that is percutaneously adjustable without the use of injections, an injection port, or TET.